Replying in a timely manner

Replying in a timely manner is a social skill.

How soon should I expect a response from you?
By Friday 7, 2011, the person replies.
There is no reply by Friday 7, 2011.

What were the causes of no reply by the due day and date?
You need to answer this question.

What are consequences of not replying in a timely manner?
You will give others the impression that you are incompetent. You will give others the impression you are inefficient or uncaring.
Your not replying in a timely manner can harm others.